Fire alarm devices such as audible horns (audible/visible or A/V), loudspeakers (speaker/visible or S/V) and visible strobes (visible only or V/O), are referred to as “notification appliances.” Typically, a fire alarm control panel (FACP) drives these devices over one or more “notification appliance circuits” (NACs). The strobes are required, for example, as an alert for the hearing-impaired, or for those in a high noise environment.
A strobe is typically made up of a high-intensity Xenon flash tube, a reflector assembly, a transparent protective dome, an electronic control circuit, a terminal block to connect the device to the NAC and a housing to install the device to a wall or ceiling.
The strobe is a notification device designed to disperse its light output in a hemispherical pattern. The light distribution must meet stringent specification for UL approval, and it typically must accurately flash at a specified rate, for example, once per second or at some multiple. Strobes in the same viewing area typically must be synchronized, as a fast flash rate or several unsynchronized strobes at the normal rate could cause susceptible people to have epileptic seizures. See for example, U.S. Pat. No. 5,886,620, incorporated by reference herein in its entirety.
A manual selector, such as a moveable jumper, typically allows manual selection of strobe intensity, as well as a visual indication of the selection to a person who can clearly see the selector.